Swash plate type refrigerant compressor of a typical structure is disclosed, e.g., by Publication of Japanese Patent Application No. 3-92587 (1991), which includes front and rear cylinder blocks axially combined together to form a cylinder block assembly and having defined therein a plurality of pairs of aligned cylinder bores, a reciprocable double-headed piston fitted in each paired cylinder bores front and rear housings bolted to the axial ends of the cylinder block assembly with a valve plate interposed between each housing and its adjacent cylinder block assembly end. The compressor further includes a drive shaft which is rotatably supported in the cylinder block assembly by a pair of front and rear radial bearings, and a swash plate fixedly mounted on the drive shaft at an angle of inclination for rotary wobbling movement in a swash plate compartment in the cylinder block assembly. The swash plate compartment communicates with a gas inlet fitting provided on the cylinder block assembly and connected to an external conduit through which refrigerant gas under a suction pressure is supplied to the compressor. Each double-headed piston is engaged with the swash plate by way of a pair of front and rear hemispherical shoes in such a way that the wobbling movement of the swash plate is converted into reciprocating movement of the piston in its associated paired cylinder bores.
A pair of front and rear suction chambers are defined by the front and rear housings and their adjacent valve plates, respectively, and the swash plate compartment filled with refrigerant gas under a suction pressure is connected with these front and rear suction chambers through a plurality of suction passages formed to extend axially through the respective cylinder blocks between any two circumferenially adjacent cylinder bores. Similarly, a pair of front and rear discharge chambers are formed on opposite ends of the compressor by the housings and the valve plates, respectively. These two discharge chambers are connected to each other by way of a plurality of discharge passages extending axially through the cylinder block assembly so that compressed refrigerant gas discharged into one of the discharge chambers flows into the other discharge chamber, from where it is delivered out of the compressor together with refrigerant gas forced out directly into the above other discharge chamber.
It is to be noted that, for any given diameter of cylinder bores in a compressor, the bores should be arranged and spaced apart circumferentially from each other in the cylinder block assembly at such a spaced distance that maintains the desired wall thickness between any two circumferentially adjacent cylinder bores for ensuring the overall strength and durability of the cylinder block assembly. Arranging cylinder bores radially toward the outer periphery of the cylinder block assembly with an attempt to increase the wall thickness will enlarge the assembly radially, thereby making the compressor itself disadvantageously larger in size. On the other hand, if the cylinder bores are arranged toward the axial center of the cylinder block assembly with an attempt to reduce the compressor size, the compressor strength will be in turn deteriorated by the reduction wall of thicknesses between the bores. As understood by those skilled in the art, the suction and discharge passages formed in the cylinder blocks are disadvantageous in that the presence of such passages reduces the wall thickness and, therefore, it is difficult to maintain the cylinder block assembly strength while achieving compactness of the compressor. The suction passages offer resistance against the flow of refrigerant gas to be admitted into the cylinder bores and, therefore, causes a pressure loss of the gas passing therethrough, thereby affecting the working efficiency of the compressor.
The above-cited compressor further includes another pair of bearings mounted on the drive shaft on opposite sides of the swash plate for receiving thrust pressure exerted by the drive shaft. Apparently, the use of two pairs of bearings is not only costly, but also complicates the compressor construction and hence takes more time and trouble to assemble the same.